Table 1. Sources of information on toxicology: database repositories for predictive systems toxicology investigations and risk assessment.

Toxicology Databases
Database Portals/Projects
Inh	Portal/Project name	Description	Data type	URL
	Safety Evaluation Ultimately Replacing Animal Testing (SEURAT -1)	•     Cluster of 7 projects and portal to 5 databases: SCR&Tox, HeMiBio, DETECTIVE, COSMOS, NOTOX, ToxBank, and COACH •     Aims to simulate repeated dosage toxicity testing in a complex physiologic but animal-free in vitro model •     Elucidation of biomarkers and analysis in stem cell derived organotypic systems •      In silico simulations to predict toxicity, tissue dosimetry, and proof of concept that new strategy accurately predicts liver toxicity in vivo	Access regulated per dataset; no inhalation data	http://www.seurat-1.eu/
	BioSharing	•     Portal of curated web-based, user- queryable registries of linked information on content standards, databases, and data policies in the life sciences; broadly covers the biological, natural, and biomedical sciences	Several databases	https://biosharing.org/biodbcore/
	EU-ToxRisk	•     Integrated European program aiming towards mechanism-based toxicity testing and risk assessment in nonanimal organotypic human in vitro models •     Applies mechanistic molecular knowledge to develop ‘Adverse Outcome Pathways,’ enabling in silico knowledge generation regarding toxicity •     Integrates information from cellular and molecular biology, computational toxicology models, and systems biology to assess toxic responses to repeated chemical exposure	Website under construction	http://www.eu-toxrisk.eu/
	Data Infrastructure for Chemical Safety (diXa)	•     Collection of European toxicogenomics experiments with crosslinks to several globally-available chemical and molecular medicine databases •     Contains data across several disciplines, including chemical toxicity, dosimetry, omics analyses, and chemical catalogues, integrated into a single resource with a focus towards the development of nonanimal tests for prediction of chemical safety	Individual cigarette smoke (CS) chemical information	http://wwwdev.ebi.ac.uk/fg/dixa/ index.html
	TOXNET	•     Collection of several databases and publications covering topics such as chemicals and drugs, diseases and the environment, environmental health, occupational safety and health, poisoning, risk assessment and regulations, and toxicology •     Provides links to PubMed and NLM interface for associated publications in biomedical toxicology field	Mostly publication abstracts and links	http://toxnet.nlm.nih.gov/
	ToxCast™/Tox21	•     Tox21 is a United States federal collaboration to develop better toxicity assessment methods. Tox21 has resulted in the screening of over 10,000 chemicals via ~50 high-throughput assays •     The EPA has contributed the chemical screening results from the Toxicity Forecaster (i.e., ToxCast™), an initiative to assess and screen ~2,000 chemicals for toxicity to cells and proteins via over 700 automated, high-throughput screening assays •     Data consist of chemicals used, assays performed, genes and pathways implicated, and endpoints	Data available via iCSS dashboard: individual CS chemical information, publication links, graphs, and assay data files	http://actor.epa.gov/dashboard/
Inh	Individual Databases
	PubChem	•     Provides information on small-molecule biochemical activity •     Specialized databases within PubChem (PCSubstance, PCCompound, PCBioAssay) contain physical and chemical properties and nomenclature of over 100 million substances •     Cross-linked entries across the three databases (Substance, Compound, and BioAssay) and NCBI Entrez •     PCBioAssay database contains bioactivity screen information, raw assay data, and readouts of screening protocols for chemical substances in PCSubstance	Publications and assay records	https://pubchem.ncbi.nlm.nih.gov/
	ChEBI	•     Dictionary of identifiable, distinct molecular entities (nucleic acids, peptides and proteins) linking various classes of entities and their parents/ children •     Follows the nomenclature and terminology laid out by IUPAC and NC- IUPAC •     The ontology classes encompass various science and engineering disciplines (e.g., nicotine is linked to its structural, chemical, and biological properties) •     Provides links to several other databases and publications for chemicals	Individual CS constituents, disease associations	https://www.ebi.ac.uk/chebi
	Comparative Toxicogenomics Database (CTD)	•     Collection of interlinked public databases with information on the effects of drugs and chemical exposure on human biochemical processes •     Manually curated information from scientific journal articles on chemical- disease and gene-disease relationships integrated with various other data, including those of pathways (e.g., KEGG) and gene ontology, to elucidate the underlying molecular landscape of environmentally borne diseases	Independent studies and publications	http://ctdbase.org/
	Aggregated Computational Toxicology Resource (ACToR)	•     Publicly available online resource for toxicity data for over 500,000 chemicals accumulated and referenced from EPA repository of toxicity databases such as ToxCastDB (chemical screening data), Exposure Data (effects of chemical exposure on humans), and DSSTox (structural and annotation information) •     Provides physicochemical, in vitro and in vivo toxicology data on many toxic substances, including industrial chemicals, pesticides, and other contaminants	Publications, reports/ surveys from other government/private agencies, and other databases and studies	http://actor.epa.gov/
	Chemical Effects in Biological Systems (CEBS)	•     Toxicogenomics database with a conglomeration of omics, classical toxicology, gene, and protein regulatory network data on human health and environmental toxicology •     User-queryable interface allows search for protocols, chemicals, endpoints, genes/proteins, tissue type, toxicological parameters, etc., to facilitate hypothesis- driven systems toxicology research and risk-assessment studies	Publications, reports/studies from government/ private agencies, databases, and independent investigations *Links ToxCast21 Phase II	https://www.niehs.nih.gov/ research/resources/databases/ cebs
	CompTox Chemistry Dashboard	•     Access to >740,000 chemical substances associated with both experimental and predicted properties		https://comptox.epa.gov
	Online Chemical Database (OCHEM)	•     Modeling tool for development of substance properties-quantitative structure-activity and structure-activity (QSPR/QSAR) models •     Repository for scientists’ models to allow cross examination and estimation of the ADMET properties of any compound		https://ochem.eu
	ToxBank	•     Subsidiary of the SEURAT-1 project that unifies all the in vitro, in vivo, and in silico data and experimental protocols under one roof to facilitate integrated data analysis •     Enables the development of an industry standard data repository to replace repeated in vivo repeated dose toxicity testing •     Compound wiki provides information on selected hepato-/cardiotoxic compounds	Access is regulated per dataset; no inhalation data	http://toxbank.net/

The table highlights sources of information on in vivo chemical inhalation and individual in vitro chemical toxicity. The type of data available and, where known, user accessibility (e.g., open source vs licensing) have also been highlighted. While a number of databases and portals are still active, a few of them are no longer maintained. Green color in the “Inh” column means that the resource contains inhalation data.